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08 1500 Cyl#7 misfire

08SILVERADO1500
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08SILVERADO1500 Enthusiast

08SILVERADO1500

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That does make sense, however mine feels like a continuous misfire as if it is a fully stuck lifter. It's not a hit and miss situation. But I'll still try this and see what happens. Pretty simple option to try with only a few bolts. 

asilverblazer Senior Enthusiast

asilverblazer

Posted
Posted (edited)
2 hours ago, 08SILVERADO1500 said:

Asilverblazer

 

I did check compression but I feel the gauge is way old and does not register correctly. 

So I feel that test is inconclusive. 

Especially, that it showed low compression and then removing the gauge thumps very loud from the spark plug port. 

Its easy to move air against no resistance.

 

Maybe check compression on all cylinders, regardless of gauge condition they should all be about the same. 

 

Do you have a vacuum gauge you can connect to manifold vacuum while the engine is running? A valve problem will be very apparent on a vacuum gauge. 

 

A burnt valve will still move, but doesn't seal. 

 

It SOUNDS like you've already addressed the easy fixes... and should be pre-paring to at least pull the head. Before I'd do that (its a lot of work), I'd make real sure by checking compression and vacuum readings. 

Edited by asilverblazer
08SILVERADO1500 Enthusiast

08SILVERADO1500

Posted
  • Author
Posted

I know, that's my last option is to pull the head. Though I do know how to do it as I've done a stuck lifter on the same side before. I believe it was in #5 but I'm not sure. A lifter definitely does not seem to be the case. I just want to find the cause. The repair is not a problem. 

I don't know if I have a vacuum gauge for the application. I know I have some but they are old units like 80's era mist likely. 

asilverblazer Senior Enthusiast

asilverblazer

Posted
Posted (edited)
30 minutes ago, 08SILVERADO1500 said:

I know, that's my last option is to pull the head. Though I do know how to do it as I've done a stuck lifter on the same side before. I believe it was in #5 but I'm not sure. A lifter definitely does not seem to be the case. I just want to find the cause. The repair is not a problem. 

I don't know if I have a vacuum gauge for the application. I know I have some but they are old units like 80's era mist likely. 

Determining the cause of failure might be easier once its determined what has failed. Lifter failure hasn't been ruled out from previous posts. These engines are more prone to those than valves. 

 

...Its a bit late to ask this in the diagnosis. Codes? (I bet there are a bunch of them.)

 

A low compression oil burning engine suggests some time at a machine shop wouldn't be out of the question. A least servicing the heads...

Edited by asilverblazer

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